Porsche 911 TURBO - 1989 Workshop Manual page 53

CHECKING FUEL PUMP DELIVERY
Note
Before checking fuel pump, check for:
-clean fuel filter
-electrical connections OK
-at least 11.5 volts at both
fuel pumps
1. Detach fuel return line
(left side of engine compartment).
4. Switch on ignition for 30 seconds. Both pumps
must deliver 140 liter/hour or 1170 cc in
30 seconds.
Note
If delivery rate is less than this specification,
check pressure of fuel pumps to determine which
pump is defective.
2. Extend fuel return line with a section of fuel
hose and place end in a measuring glass
(contents about 1500 cc).
CHECKING PUMP PRESSURE
3. Bridge both fuel pump relays (30 and 87) or
pullout plug on air sensor contact.
1. Loosen intake fuelline.
-II, 1976
20 -3
Printed in Germany
Checking Fuel Pump Delivery